A 20 nanometer (nm) wavelength spacing is used in conventional Coarse Wave Division Multiplexing (CWDM) optical communication networks. This wide spacing allows for the use of inexpensive optical components where the propagation distance is limited to under 30 km. However, when using 20 nm spacing effects such as Stimulated Brillouin Scattering (SBS) and/or Stimulated Raman Scattering can induce second and third order crosstalk effects that limit the distance that usable optical signals may propagate over optical fiber.
Longer distances may be achieved by increasing the power at which optical signals are generated at the source. However, SBS and/or SRS effects may increase with increases in optical power. This may limit the number of wavelengths that may be used over a particular distance at a certain optical transmission power. For example, with 20 nm wavelength spacing two (2) wavelengths may be used at 7 dBm optical power over distances of around 15-20 km. Three (3) wavelengths may be used at over distances of around 10-15 km when the optical power is reduced to 4 dBm.